Media captionThe BBC's Gabriel Gatehouse: "As a policeman tried to stop the man, he detonated the explosives inside his vest"

A suicide bomber has killed at least 43 people and injured 40 more southwest of Baghdad, Iraqi police say.

The attack targeted government-backed Sunni militia members lining up to be paid in the neighbourhood of Radwaniya.

The Sunni militia fighters, known as the Sahwa or Awakening Councils, were once allied with al-Qaeda, but turned against the militant group in 2006.

Among the dead were at least six soldiers and three accountants, the Associated Press news agency reported.

At least 13 soldiers were also wounded, along with four accountants.

"There were more than 85 people lined up in three lines at the main gate of the military base to receive salaries when a person approached us," a survivor, 20-year-old Tayseer Mehsen, told the Reuters news agency at Mahmudiya hospital.

The BBC's Gabriel Gatehouse in Baghdad says the Sahwa are credited with helping to reduce the overall levels of violence in Iraq since they joined the US military and government forces in the fight against al-Qaeda.

He says that the Sahwa have been increasinly targeted by militants in recent months and have complained that their state-support is evaporating.

The Sons of Iraq, as members of the militia are also known, have recently reported cases of harassment from government troops as a political vacuum continues following inconclusive elections in March.

Sunni insurgents have sought to exploit the deadlock created by a failure of Sunni, Shia and Kurdish factions to agree on a new coalition government.

The two lists which won most seats are still bickering over who should be the next prime minister.

Both former prime minister Iyad Allawi and incumbent Nouri Maliki insist that they are best placed to lead the war-torn country.

There are fears that the political uncertainty could hinder the planned withdrawal of all US combat troops from Iraq by the end of August, in preparation for a full military departure by 2012.

In a second attack, a suicide bomber killed at least three people and wounded six at a meeting of Sunni militia leaders in western Iraq, police said.